User talk:130.226.87.140

November 2019
Hello, I'm 78.26. I noticed that you added or changed content in an article, Opportunity cost, but you didn't provide a reliable source. It's been removed and archived in the page history for now, but if you'd like to include a citation and re-add it, please do so. You can have a look at the tutorial on citing sources, or if you think I made a mistake, you can leave me a message on my talk page. Thank you. 78.26 (spin me / revolutions) 14:34, 27 November 2019 (UTC)
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